Providing Efficiencies in Processing and Communicating Internet Protocol Packets in a Network Using Segment Routing

ABSTRACT

In one embodiment, a Segment Routing network node provides efficiencies in processing and communicating Internet Protocol packets in a network. An Internet Protocol (IP) packet, possibly a Segment Routing packet, is received by a node in a network, which updates the packet according to a corresponding Segment Routing Policy, that includes an ordered list of Segment Identifiers comprising, in first-to-last order, a first Segment Identifier followed by one or more subsequent Segment Identifiers. The updating of the packet includes setting the Destination Address to the first Segment Identifier, and adding said one or more subsequent Segment Identifiers, but not the first Segment Identifier, in a first Segment Routing Header. The updated packet is sent into the network without the first Segment Identifier being added to a Segment Routing Header in response to the Segment Routing Policy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/525,439, filed Jun. 27, 2017, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to processing and sending ofInternet Protocol packets in packet network, such as, but not limitedto, adding and communicating packets according to a Segment RoutingPolicy.

BACKGROUND

The communications industry is rapidly changing to adjust to emergingtechnologies and ever increasing customer demand. This customer demandfor new applications and increased performance of existing applicationsis driving communications network and system providers to employnetworks and systems having greater speed and capacity (e.g., greaterbandwidth). In trying to achieve these goals, a common approach taken bymany communications providers is to use packet switching technology.Packets are typically forwarded in a network based on one or more valuesrepresenting network nodes or paths.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims set forth the features of one or more embodimentswith particularity. The embodiment(s), together with its advantages, maybe understood from the following detailed description taken inconjunction with the accompanying drawings of which:

FIG. 1A illustrates a network operating according to one embodiment;

FIG. 1B illustrates a process according to one embodiment;

FIG. 2A illustrates a packet switching device according to oneembodiment;

FIG. 2B illustrates an apparatus according to one embodiment;

FIG. 3A illustrates a Segment Routing packet according to oneembodiment;

FIG. 3B illustrates a network operating according to one embodiment;

FIG. 4 illustrates a process according to one embodiment;

FIG. 5A illustrates packet processing of a packet according to oneembodiment;

FIG. 5B illustrates a process according to one embodiment;

FIG. 6A illustrates packet processing of a packet according to oneembodiment;

FIG. 6B illustrates a process according to one embodiment;

FIG. 6C illustrates packet processing of a packet according to oneembodiment;

FIG. 6D illustrates a process according to one embodiment;

FIG. 7A illustrates packet processing of a packet according to oneembodiment;

FIG. 7B illustrates a process according to one embodiment;

FIG. 8A illustrates packet processing of a packet according to oneembodiment;

FIG. 8B illustrates a process according to one embodiment;

FIG. 8C illustrates packet processing of a packet according to oneembodiment;

FIG. 8D illustrates a process according to one embodiment;

FIG. 9A illustrates packet processing of a packet according to oneembodiment;

FIG. 9B illustrates packet processing of a packet according to oneembodiment;

FIG. 9C illustrates a process according to one embodiment;

FIG. 10A illustrates packet processing of a packet according to oneembodiment; and

FIG. 10B illustrates a process according to one embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS 1. Overview

Disclosed are, inter alia, methods, apparatus, computer-storage media,mechanisms, and means associated with providing efficiencies inprocessing and communicating Internet Protocol packets in a networkusing Segment Routing.

In one embodiment, a particular packet is received by a particular nodein a network, with the particular packet including an outer InternetProtocol version 6 (IPv6) header that includes a Destination Address.The received particular packet is updated according to a particularSegment Routing Policy identified based on the particular packet. Theparticular Segment Routing Policy includes an ordered list of SegmentIdentifiers comprising, in first-to-last order, a first SegmentIdentifier followed by one or more subsequent Segment Identifiers. Theupdating of the particular packet includes setting the DestinationAddress to the first Segment Identifier, and adding said one or moresubsequent Segment Identifiers, but not the first Segment Identifier, ina first Segment Routing Header. The updated particular packet is sentinto the network without the first Segment Identifier being added to aSegment Routing Header in response to the Segment Routing Policy.

In one embodiment, a particular Internet Protocol (IP) packet isreceived by a network node in a network. The particular IP packet isupdated by the network node to include a particular Segment RoutingPolicy, with the Segment Routing Policy including an ordered list ofSegment Identifiers that will be traversed by the particular IP packet.This ordered list comprises, in first-to-last order, a first SegmentIdentifier followed by one or more subsequent Segment Identifiers. Thisupdating includes: adding said one or more subsequent SegmentIdentifiers to a first Segment Routing Header that is an IP Extensionheader of the particular IP packet; and setting the Destination Addressof the outer IP header of the particular IP packet to the first SegmentIdentifier; while not including adding the first Segment Identifier toany Segment Routing header of the particular IP packet. The updatedparticular IP packet is sent from the network node into the network.

In one embodiment, the received packet is a Segment Routing packet. Inone embodiment, the received particular packet is an IPv6 packet, butnot a Segment Routing packet. In one embodiment, updating the particularIP packet includes adding the value, when the particular packet was saidreceived by the particular node, of the Destination Address as a SegmentIdentifier in a Segment Routing Header of the particular IP packet thatis the next in Segment Identifier processing order for said updatedparticular IP packet after said one or more subsequent SegmentIdentifiers. In one embodiment, the received particular packet is anIPv6 Segment Routing packet including a particular Segment RoutingHeader; and wherein said updating the particular packet includesinserting the first Segment Routing Header in the particular packetbetween the outer IPv6 header and the particular Segment Routing Header,and increasing the Segments Left value by one in the particular SegmentRouting Header.

2. Description

Disclosed are, inter alia, methods, apparatus, computer-storage media,mechanisms, and means associated with providing efficiencies inprocessing and communicating Internet Protocol packets in a networkusing Segment Routing.

As used herein Segment Routing includes using Internet Protocol Version6 (IPv6) addresses as Segment Identifiers (SIDs); in other words, asused herein, Segment Routing includes IPv6 Segment Routing (SRv6). Asused herein, a Segment Routing node refers to a network node (e.g.,router, server, appliance) that performs Segment Routing functionality,including, but not limited to, adding, updating, or removing a SegmentRouting Header; performing a Segment Routing function identified by aSegment Identifier that is the IP Destination Address of an IP packet oris a Segment Identifier in a Segment Routing Header. Also, as usedherein, an IP packet may or not be a Segment Routing Packet; but aSegment Routing packet is an IP packet.

The term “outer IP header” of a packet refers to the IP header (not anExtension header) used in processing and forwarding of the packet, anddoes not refer to a header of a packet encapsulated (e.g., in thepayload) of the packet. The term “IP Destination Address” refers to thevalue of the IP Destination Address field of the outer IP header. Thephrase “wherein the value, when the particular packet was said receivedby the particular node, of the Destination Address” refers to IPDestination Address of the packet when the packet was received by theparticular node, which may or may not be the same as the IP DestinationAddress of the packet when sent from the particular node.

The terms “node” or “network node” are used herein to refer to a routeror host. The term “route” is used herein to refer to a fully orpartially expanded prefix/route (e.g., 10.0.0.1 or 10.0.*.*), which isdifferent than a “path” through the network which refers to a nexthop(e.g., next router) or complete path (e.g., traverse router A thenrouter B, and so on). Also, the use of the term “prefix” without aqualifier herein refers to a fully or partially expanded prefix. Also,as used herein, “forwarding information” includes, but is not limitedto, information describing how to process (e.g., forward, send,manipulate, modify, change, drop, copy, duplicate, receive)corresponding packets. In one embodiment, determining forwardinginformation is performed via an ingress lookup operation and an egresslookup operation. Also, the term “processing” when referring toprocessing of a packet process refers to a broad scope of operationsperformed in response to a packet, such as, but not limited to,forwarding/sending, dropping, manipulating/modifying/changing,receiving, duplicating, creating, applying one or more service orapplication functions to the packet or to the packet switching device(e.g., updating information), etc. Also, as used herein, the termprocessing in “parallel” is used in the general sense that at least aportion of two or more operations are performed overlapping in time.

As described herein, embodiments include various elements andlimitations, with no one element or limitation contemplated as being acritical element or limitation. Each of the claims individually recitesan aspect of the embodiment in its entirety. Moreover, some embodimentsdescribed may include, but are not limited to, inter alia, systems,networks, integrated circuit chips, embedded processors, ASICs, methods,and computer-readable media containing instructions. One or multiplesystems, devices, components, etc., may comprise one or moreembodiments, which may include some elements or limitations of a claimbeing performed by the same or different systems, devices, components,etc. A processing element may be a general processor, task-specificprocessor, a core of one or more processors, or other co-located,resource-sharing implementation for performing the correspondingprocessing. The embodiments described hereinafter embody various aspectsand configurations, with the figures illustrating exemplary andnon-limiting configurations. Computer-readable media and means forperforming methods and processing block operations (e.g., a processorand memory or other apparatus configured to perform such operations) aredisclosed and are in keeping with the extensible scope of theembodiments. The term “apparatus” is used consistently herein with itscommon definition of an appliance or device.

The steps, connections, and processing of signals and informationillustrated in the figures, including, but not limited to, any block andflow diagrams and message sequence charts, may typically be performed inthe same or in a different serial or parallel ordering and/or bydifferent components and/or processes, threads, etc., and/or overdifferent connections and be combined with other functions in otherembodiments, unless this disables the embodiment or a sequence isexplicitly or implicitly required (e.g., for a sequence of read thevalue, process said read value—the value must be obtained prior toprocessing it, although some of the associated processing may beperformed prior to, concurrently with, and/or after the read operation).Also, nothing described or referenced in this document is admitted asprior art to this application unless explicitly so stated.

The term “one embodiment” is used herein to reference a particularembodiment, wherein each reference to “one embodiment” may refer to adifferent embodiment, and the use of the term repeatedly herein indescribing associated features, elements and/or limitations does notestablish a cumulative set of associated features, elements and/orlimitations that each and every embodiment must include, although anembodiment typically may include all these features, elements and/orlimitations. In addition, the terms “first,” “second,” etc., as well as“particular” and “specific” are typically used herein to denotedifferent units (e.g., a first widget or operation, a second widget oroperation, a particular widget or operation, a specific widget oroperation). The use of these terms herein does not necessarily connotean ordering such as one unit, operation or event occurring or comingbefore another or another characterization, but rather provides amechanism to distinguish between elements units. Moreover, the phrases“based on x” and “in response to x” are used to indicate a minimum setof items “x” from which something is derived or caused, wherein “x” isextensible and does not necessarily describe a complete list of items onwhich the operation is performed, etc. Additionally, the phrase “coupledto” is used to indicate some level of direct or indirect connectionbetween two elements or devices, with the coupling device or devicesmodifying or not modifying the coupled signal or communicatedinformation. Moreover, the term “or” is used herein to identify aselection of one or more, including all, of the conjunctive items.Additionally, the transitional term “comprising,” which is synonymouswith “including,” “containing,” or “characterized by,” is inclusive oropen-ended and does not exclude additional, unrecited elements or methodsteps. Finally, the term “particular machine,” when recited in a methodclaim for performing steps, refers to a particular machine within the 35USC § 101 machine statutory class.

FIG. 1A illustrates a network 100 (e.g., an aggregation of one or morenetworks of one or more different entities) operating according to oneembodiment. As shown, network 100 includes client networks 101 and 103(which are the same network in one embodiment) communicatively coupledto Segment Routing (SR) provider network 110. In one embodiment, each ofclient networks 101 and 103 include hosts (e.g., end nodes) withupper-layer applications that communicate via network 100. In oneembodiment, some of the hosts in client network 101 and/or 103 areSR-capable in that they can generate and process Segment Routingpackets.

In one embodiment, Segment Routing network 110 (e.g., a providernetwork) includes Segment Routing edge nodes 111 and 113, and a network112 of network nodes including SR-capable routers (and possibly somethat are not SR-capable in that they do not process a Segment Routingheader/complete Segment Identifier), SR gateways, service functions, andhosts (e.g., end nodes). In one embodiment, SR edge nodes 111 and 113process packets received from networks 101 and 103, which may includeencapsulating or otherwise processing these packets into SR packets suchas by adding a SR header (and possibly another IP header) to thesepackets according to a data plane ascertained Segment Routing policy,and subsequently decapsulating or removing a Segment Routing header (andpossibly another IP header) and forwarding the native (Segment Routingor IP) packets into network 101 and 103.

In one embodiment and in response to receiving a packet, a SegmentRouting edge node 111, 113 and/or a Segment Routing node within network112 determines a Segment Routing policy (e.g., list of complete SegmentIdentifiers) through and/or to which to forward a Segment Routing packetencapsulating the native packet. These policies can change in responseto network conditions, network programming, etc. In one embodiment, theSegment Routing policy specifies to add one or more SR headers, eachwith one or more Segment Identifiers, resulting in a Segment Routingpacket having one or more Segment Routing headers. In one embodiment, anative packet is received without a Segment Routing header (possiblywith an IP Destination Address that is a Segment Identifier/IP addressof the receiving Segment Routing node), and the Segment Routing nodeencapsulates the native packet in a Segment Routing packet including oneor more added Segment Routing headers, each including one or moreSegment Identifiers. In one embodiment, a Segment Routing packet isreceived with a Segment Routing header, and with Segment Routing nodeadding one or more Segment Routing headers resulting in a SegmentRouting packet including one or more added Segment Routing headers, eachincluding one or more Segment Identifiers. In contrast, and for each ofthese scenarios a single Segment Routing header could have been usedthat includes all of the Segment Identifiers.

FIG. 1B illustrates a process according to one embodiment associatedwith providing efficiencies in processing and communicating InternetProtocol packets in a network using Segment Routing. Processing beginswith process block 160. In process block 162, routers in the networkscontinuously advertise and exchange routing information includingSegment Routing information (e.g., routes including Segment Identifiersof network nodes and their corresponding function or function/arguments,attributes of Segment Identifiers, attributes of node) and other routinginformation (e.g., IPv4 or IPv6 topology information) typically via oneor more routing protocols and/or other protocols. In process block 164,Segment Routing and other network nodes continuously update theirSegment Routing policies and routing/forwarding information as required(e.g., based on information received via a routing or other protocol,from a network management system, etc.). Processing of the flow diagramof FIG. 1B is complete as indicated by process block 169.

FIGS. 2A-B and their discussion herein provide a description of variousnetwork nodes according to one embodiment.

FIG. 2A illustrates one embodiment of a packet switching device 200(e.g., router, node, appliance, gateway) according to one embodiment. Asshown, packet switching device 200 includes multiple line cards 201 and205, each with one or more network interfaces for sending and receivingpackets over communications links (e.g., possibly part of a linkaggregation group), and with one or more processing elements that areused in one embodiment associated with providing efficiencies inprocessing and communicating Internet Protocol packets in a networkusing Segment Routing. Packet switching device 200 also has a controlplane with one or more processing elements (e.g., Route Processor(s))202 for managing the control plane and/or control plane processing ofpackets associated with providing efficiencies in processing andcommunicating Internet Protocol packets in a network using SegmentRouting. Packet switching device 200 also includes other cards 204(e.g., service cards, blades) which include processing elements that areused in one embodiment to process (e.g., forward/send, drop, manipulate,change, modify, receive, create, duplicate, perform SR functionalitypossibly with shared memory with one or more service functions, apply aservice according to one or more service functions) packets associatedwith providing efficiencies in processing and communicating InternetProtocol packets in a network using Segment Routing, and somehardware-based communication mechanism 203 (e.g., bus, switching fabric,and/or matrix, etc.) for allowing its different entities 201, 202, 204and 205 to communicate. Line cards 201 and 205 typically perform theactions of being both an ingress and egress line card, in regards tomultiple other particular packets and/or packet streams being receivedby, or sent from, packet switching device 200. In one embodiment,Segment Routing functions are implemented on line cards 201, 205.

FIG. 2B is a block diagram of an apparatus 220 (e.g., host, router,node, destination, or portion thereof) used in one embodiment associatedwith providing efficiencies in processing and communicating InternetProtocol packets in a network using Segment Routing. In one embodiment,apparatus 220 performs one or more processes, or portions thereof,corresponding to one of the flow diagrams illustrated or otherwisedescribed herein, and/or illustrated in another diagram or otherwisedescribed herein.

In one embodiment, apparatus 220 includes one or more processor(s) 221(typically with on-chip memory), memory 222 (possibly shared memory),storage device(s) 223, specialized component(s) 225 (e.g. optimizedhardware such as for performing lookup, packet processing (includingSegment Routing processing) and/or service function operations;associative memory; binary and/or ternary content-addressable memory;Application Specific Integrated Circuit(s), etc.), and interface(s) 227for communicating information (e.g., sending and receiving packets,user-interfaces, displaying information, etc.), which are typicallycommunicatively coupled via one or more communications mechanisms 229(e.g., bus, links, switching fabric, matrix), with the communicationspaths typically tailored to meet the needs of a particular application.

Various embodiments of apparatus 220 may include more or fewer elements.The operation of apparatus 220 is typically controlled by processor(s)221 using memory 222 and storage device(s) 223 to perform one or moretasks or processes. Memory 222 is one type ofcomputer-readable/computer-storage medium, and typically comprisesrandom access memory (RAM), read only memory (ROM), flash memory,integrated circuits, and/or other memory components. Memory 222typically stores computer-executable instructions to be executed byprocessor(s) 221 and/or data which is manipulated by processor(s) 221for implementing functionality in accordance with an embodiment. Storagedevice(s) 223 are another type of computer-readable medium, andtypically comprise solid state storage media, disk drives, diskettes,networked services, tape drives, and other storage devices. Storagedevice(s) 223 typically store computer-executable instructions to beexecuted by processor(s) 221 and/or data which is manipulated byprocessor(s) 221 for implementing functionality in accordance with anembodiment.

FIG. 3A illustrates a SRv6 packet 320 according to one embodiment. Asshown, SRv6 packet 320 includes an outer IPv6 header 321 (which, asshown, includes a Destination Address of value S1::, and othervalues/fields), one or more Segment Routing headers 322, and a payloadfield 323 that typically includes application data, encapsulatedpackets, and/or other values. As shown, Segment Routing header 310includes a Segment List with two ordered Segment List elements (eachstoring a Segment Identifier that is an IPv6 address) with values ofSegment Identifiers C:: and S2::, and with Segments Left having a valueof two [2].

One embodiment improves processing and network efficiencies by notincluding redundant Segment Routing/forwarding information in a packet,albeit in violation of standardized Segment Routing requirements. Oneembodiment, in creating a Segment Routing Packet or modifying a SegmentRouting Packet (e.g., to add one or more Segment Identifiers of aSegment Routing Policy), does not include in the Segments List the firstsixteen-byte Segment Routing Identifier of this Segment RoutingPolicy—as the IP Destination Address of the packet being create ormodified is set to this sixteen-byte value. Any additional SegmentRouting Identifier(s) of the Segment Routing Policy are added to theSegments List to be processed in order. Also, the value of the SegmentsLeft is set to a value equal (or possibly greater) than the number ofSegment Identifiers in the Segment List, in order to communicate to areceiving Segment Routing node that the current Segment Identifier ofthe Segment Routing Policy is not included in the Segment List, butrather only as the IPv6 Destination Address (e.g., S1:: in outer IPv6header 321).

In one embodiment, for a Segment Routing Policy with n+1 SegmentIdentifiers, the processing/traversal order of these Segment Identifiersis the first Segment Identifier in the Destination Address of the outerIP header, followed by the n Segment Identifiers stored in the n SegmentList elements.

In a Segment List with n Segment List elements (each storing a SegmentIdentifier), the processing/traversal order proceeds from Segment Listelement [n−1] at the bottom of the Segment List (furthest from thebeginning of its Segment Routing header) to Segment List element [0] atthe top of the Segment List (closest to the beginning of its SegmentRouting header). Segments Left identifies a Segment List element in theSegment List (e.g., a segments left value of zero identifies the SegmentIdentifier at the top of the Segment List and identifies a SegmentIdentifier above all other Segment Identifiers in the Segment List), ora Segment Identifier not in the Segment List but only stored as the IPDestination address in the packet.

Also shown in FIG. 3A and according to one embodiment, SegmentIdentifier (SID) 316 includes locator 317 with a value of S2::, function318 with a value of zero, and argument 319 of zero. A non-zero value offunction 318 (with a zero or non-zero or argument 319) is typically usedin a network to identify a Segment Routing function that will causecorresponding processing to be performed.

FIG. 3B illustrates a network 360 operating according to one embodiment.Network 360 includes client network 362 (with source node 361 having anIPv6 address of M::) and client network 368 (with destination node 369having an IPv6 address of N::). Network 360 also includes providernetwork 330, that includes provider nodes 331-336 (e.g., Segment Routingrouters). SR Router 331 has an IPv6 address of A::, SR Router 332 has IPAddresses of B:: and B::8, SR Router 333 has an IPv6 address of S1::, SRRouter 334 has an IPv6 address of S2::, SR Router 335 has an IPv6address of C::, and SR Router 336 has an IPv6 address of D::. EachRouter 331-336 typically advertises all of their IP addresses using arouting or other protocol.

FIG. 3B shows packet 320 (denoted 320A, 320B, 320C, 320E, 320F, and320G) being communicated in network 360 from source node 361 todestination node 369. Even though packet 320 is modified in network 360by a network node 331-336, packet 320 (320A-G) is still considered asame packet.

As shown in FIG. 3B, source node 361 sends an IPv6 packet 320A with aDestination Address of N:: into client network 362. Packet 320 A isreceived by SR node 331, which sends IPv6 or SRv6 packet 320B to SR node332, that sends SRv6 packet 320C to SR node 333, that sends SRv6 packet320D to SR node 334, that sends SRV6 packet 320E to SR node 335, thatsends SRv6 or IPv6 packet 320F to SR node 336, that sends IPv6 packet320G to client network 368 which routes it to destination node 369.

The figures subsequent to FIG. 3B herein often refer to a particularversion of the packet 320A-320G shown in FIG. 3B to provide context,such as for, but not limited to, the changing of a received non-SegmentRouting IPv6 packet in a SRv6 packet.

FIG. 4 illustrates a process according to one embodiment. Processingbegins with process block 400. In process block 402, a Segment Routingnode (e.g., router) receives an IP packet. As determined in processblock 403, if the packet includes a Segment Routing Header (SRH), thenprocessing proceeds to process block 405; otherwise processing proceedsto process block 410. As determined in process block 405, if the IPDestination Address is a Segment Identifier referring to a local SegmentRouting function, then processing proceeds to process block 406;otherwise processing proceeds to process block 410.

Continuing in process block 410, an ingress lookup operation (e.g.,packet classification) is performed to determine forwarding informationfor the received packet. As determined in process block 411, if theforwarding information defines to perform a transit Segment Routingfunction (e.g., the IP Destination Address is not an IP address of thenode and the forwarding information determines to perform a SegmentRouting function), then processing proceeds to process block 406;otherwise processing proceeds to process block 412.

Continuing in process block 406, the packet is processed according tothe corresponding Segment Routing function, and processing proceeds toprocess block 414.

Continuing in process block 412, the packet is processed according tothe identified forwarding information, and processing proceeds toprocess block 414.

Continuing in process block 414, an egress lookup operation is performedto identify forwarding information, with the processed packet (e.g.,that was not dropped by such processing) is forwarded accordingly.Processing of the flow diagram of FIG. 4 is complete as indicated byprocess block 419.

FIG. 5A illustrates Segment Routing packet processing of IPv6 packet320B (with outer IPv6 header 500) according to one embodiment. Inresponse to receiving packet 320B, a Segment Routing Policy of SegmentIdentifiers S:: then S2:: is identified and added to IPv6 packet 320Bresulting in SRv6 packet 320C. SRv6 packet 320C has the same IP Source501 address, has its Destination Address (in outer IPv6 header 510) setto the first Segment Identifier 512, and has the same payload 503.Additionally, Segment Routing Header 520 is added including intraversing order Segment Identifier S2:: (523) from the Segment RoutingPolicy), and Segment Identifier N:: (502) from the Destination Address502 of received IPv6 packet 320B. Segments Left 521 is set to two (asthere are two Segment Identifiers in SR header 520) indicating that thenext Segment Identifier is only stored as Destination Address 512, andnot in Segment Routing Header 520. Note, Segment Routing node 333 ofFIG. 3B having IP address S1:: will receive packet 320C, and inresponse, will decrease Segments Left 521 by one, thus pointing toSegment Identifier S2:: (523).

FIG. 5B illustrates a process according to one embodiment. Processingbegins with process block 580. In process block 582, the DestinationAddress of the received packet is updated to that of the first SegmentIdentifier of the Segment Routing Policy being inserted (with the SourceAddress remaining the same), but this Segment Identifier is not includedin the SR Header being inserted in the received packet. In process block584, a SR Header is inserted right after the outer IP header, with thelast Segment Identifier set to the Destination Address of the receivedpacket. The remaining Segment Identifiers of the Segment Routing Policyare accordingly included in the SR Header, with its Segments Left to thenumber of Segment Identifiers in the SR Header. Processing of the flowdiagram of FIG. 5B is complete as indicated by process block 589.

FIG. 6A illustrates Segment Routing packet processing of a received IPv6packet 320B according to one embodiment. This processing is similar tothat illustrated in FIG. 5A, but uses two SR Headers 630, 640.

In response to receiving packet 320B, a Segment Routing Policy ofSegment Identifiers S1:: then S2:: is identified and added to IPv6packet 320B resulting in to SRv6 packet 320C. SRv6 packet 320C has thesame IP Source 601 address, has its Destination Address (in outer IPv6header 610) set to the first Segment Identifier 622, and has the samepayload 603.

SR Header 640 is added with the single Segment Identifier 602 copiedfrom Destination Address 602 of received IPv6 packet 320B. Segments Leftis set to one (the number of Segment Identifiers in SR Header 640) asthe current Segment Identifier is not in the Segment List of SR Header640.

SR Header 630 (which will be completely processed prior to SR Header640) is added including Segment Identifier S2:: (632) from the SegmentRouting Policy. Segments Left 631 is set to one as the current SegmentIdentifier (S1::) is only included in IP Destination Address 622, andnot in SR Header 630. One embodiment has more Segment Identifiers in theSegment Routing Policy being added, with these additional SegmentIdentifiers included in SR Header 630 and Segments Left 631 increasedaccordingly.

Note, in response to receiving packet 320C, Segment Routing node 333 ofFIG. 3B having IP address S1:: will decrease Segments Left 631 by one,thus pointing to Segment Identifier S2:: (632).

FIG. 6B illustrates a process according to one embodiment. Processingbegins with process block 680. In process block 682, the DestinationAddress of the packet is set to the first Segment Identifier of theSegment Routing Policy being inserted (with the Source Address remainingthe same), but this Segment Identifier is not included in a SR Headerbeing inserted in the received packet.

In process block 684, two SR Headers (which are IP Extension headers)are inserted into the packet right after the outer IP header. The firstSR Header includes the remaining Segment Identifiers of the SegmentRouting Policy being inserted in the packet, with its Segments Left setto this number of Segment Identifiers. A second SR Header is added tothe packet with the single Segment Identifier of the Destination Addressof the received packet, and with its Segments Left set to one.Processing of the flow diagram of FIG. 6B is complete as indicated byprocess block 689.

FIG. 6C illustrates Segment Routing packet processing of a received IPv6packet 320B according to one embodiment resulting in SRv6 packet 320,which is the same packets shown in FIG. 6A. The Segment Routing packetprocessing expressly shown in FIG. 6C includes optimizations to reduceand/or minimize the number of processing cycles required.

In one embodiment, received IPv6 packet 320 is stored in contiguousmemory locations. Bottom portion 670, from the Destination Addressthrough payload 306 of received packet 320B remains in place, with thisDestination Address being the single Segment Identifier in the second SRHeader. The first portion (e.g., twenty-four bytes) of received packet320B is moved in memory to location 661 to provide space for the addedSegment Routing Policy in two SR Headers (denoted top portion 660). Theremaining fields of top portion 660 are populated as follows: the firstSegment Identifier of the Segment Routing Policy being added is placedin location 622 (the Destination Address field of SRv6 packet 320C); thesecond SR Header 630 (as described in relation to FIG. 6A) that includesthe remaining Segment Identifiers of the Segment Routing Policy andSegments Left set to the number of these Segment Identifiers; andpreceding portion 664 of the second SR Header 640 (of FIG. 6A) with theremainder of the second SR Header 640 being Segment Identifier 602 (theremaining in place Destination Address of received packet 320B).

Further, as values (and sizes thereof) inserted in fields/locations 622,630, 644 for a particular Segment Routing Policy do not change fordifferent packets, this information can be pre-stored in a scratchpad orother memory space and directly copied into packets. This size alsodetermines where the first portion 661 (e.g., twenty-four bytes) of thereceived packet is block moved.

FIG. 6D illustrates a process according to one embodiment. Processingbegins with process block 690. In process block 692, the firsttwenty-four bytes of the outer IPv6 header of the received packet ismoved to provide space to insert SR Header information, with theDestination Address to become part of the second SR Header. In processblock 694, the second SR Header is completed by adding its first eightbytes. In process block 696, the first SR header is added with theremaining Segment Identifiers of the added Segment Routing Policy. Inprocess block 698, the Destination Address of the SRv6 packet to be sentis updated with the first Segment Identifier of the added SegmentRouting Policy. In one embodiment, the processing of process blocks694-698 is performed in a single block memory update. Processing of theflow diagram of FIG. 6D is complete as indicated by process block 699.

FIG. 7A illustrates packet processing of a received IPv6 packet 320Baccording to one embodiment to encapsulate the received packet in SRv6packet 320C. Outer IPv6 header of SRv6 packet 320C includes as SourceAddress 721 that is a local address of the node (e.g., B:: of node 332of FIG. 3B) processing received packet 320B as shown and then sendingpacket 320C; and Destination Address 722 from the first SegmentIdentifier of the Segment Routing Policy being added. SR Header 730 ofSRv6 packet 320C includes the remaining one or more Segment Identifiers732 from the added Segment Routing Policy, with Segments Left 731 set tothe number of these Segment Identifiers; and received IPv6 packet 320Bas its payload 740 (e.g., the received packet encapsulated therein).

FIG. 7B illustrates a process according to one embodiment. Processingbegins with process block 780. In process block 782, the Source Addressof the packet is set to an address of the processing node, and theDestination Address of the packet is set to the first Segment Identifierof the Segment Routing Policy being inserted, but this SegmentIdentifier is not included in a SR Header being inserted in the receivedpacket. The received packet becomes the payload of the SRv6 packet to besent. In process block 784, a SR Header is inserted right after theouter IP header, with the remaining Segment Identifiers of the SegmentRouting Policy included in the SR Header, with its Segments Left to thenumber of Segment Identifiers in the SR Header. Processing of the flowdiagram of FIG. 7B is complete as indicated by process block 789.

FIG. 8A illustrates packet processing of a received SRv6 packet 320Baccording to one embodiment. Received SRv6 packet 320B includes outerIPv6 header 800 that includes Source Address 801; and SR Header 810,that includes three Segment Identifiers and with Segments Left 811Abeing two (thus pointing to the Segment Identifier having a value ofC::). Referring to FIG. 3B, this packet processing is being performed bySR node 332, which does not have a destination address of C::. However,SR node 332 identifies (e.g., based on a lookup operation/packetclassification) on packet 320B to add the Segment Routing Policy of S1::then S2::.

In response, SRv6 packet 320C is generated with its outer IPv6 header820 including the same Source Address 801 and with its DestinationAddress 822 set to the first Segment Identifier of the Segment RoutingPolicy being added. A SR header 830 is added to include the remainingSegment Identifiers 832 of the Segment Routing Policy being added. Theremaining portion 840 of packet 320C is SR Header 810 and payload ofreceived SRv6 packet 320B, with the Segments Left 811B being one greaterthan Segments Left 811A such that SR Header 830 does not need to includethe Destination Address of received SRv6 packet 320B as a SegmentIdentifier (as Segments Left 811B would be two per Segments Left 811A).

FIG. 8B illustrates a process according to one embodiment. Processingbegins with process block 880. As determined in process block 881, ifthe packet received includes a (topmost) SR Header and Segments Left isless than the number of Segment Identifiers in this SR Header, thenprocessing proceeds to process block 884; else processing continues toprocess block 882.

Continuing in process block 884, the Segments Left is increased by onein the topmost/first SR Header of the received packet. In process block886, the Destination Address of the packet is set to the first SegmentIdentifier of the Segment Routing Policy being inserted (with the SourceAddress remaining the same), but this Segment Identifier is not includedin a SR Header being inserted in the packet. In process block 888, a SRHeader is inserted between the outer IP header and the topmost/first SRHeader of the received packet, with the remaining Segment Identifiers ofthe Segment Routing Policy included in this SR Header, with its SegmentsLeft to the number of Segment Identifiers in this SR Header. Processingproceeds to process block 889.

Continuing in process block 882, the packet is dropped or other errorprocessing is performed. Processing proceeds to process block 889.

Continuing in process block 889, processing of the flow diagram of FIG.8B is complete.

FIG. 8C illustrates packet processing of a received SRv6 packet 320Baccording to one embodiment. This processing is very similar to that ofFIG. 8A including generation of Outer IPv6 header 850 and SR Header 860,but received packet 320B does not include Destination Address 852 (ofvalue C::) as a Segment Identifier in its SR header. Thus, DestinationAddress 852 (of value C::) is added to SR Header 860, thus leaving theSegments Left value in the SR Header to be the same as when SRv6 packet320B was received. The SR Header and payload of received SRv6 packet320B is used as portion 870 of SRv6 packet 320C.

FIG. 8D illustrates a process according to one embodiment. Processingbegins with process block 890. As determined in process block 891, ifthe Segments Left is greater than zero (in the first/topmost SR Headerof received SRv6 packet 320B), then processing proceeds to process block894; else processing continues to process block 892.

Continuing in process block 894, the Destination Address of the packetis set to the first Segment Identifier of the Segment Routing Policybeing inserted (with the Source Address remaining the same), but thisSegment Identifier is not included in a SR Header being inserted in thepacket. In process block 896, a SR Header is inserted between the outerIP header and the topmost/first SR Header of the received packet, withthe remaining Segment Identifiers of the Segment Routing Policy includedin this SR Header as well as the Destination Address of the receivedSRv6 packet, with its Segments Left to the number of Segment Identifiersin this SR Header. Processing proceeds to process block 899.

Continuing in process block 892, the packet is dropped or other errorprocessing is performed. Processing proceeds to process block 899.

Continuing in process block 899, processing of the flow diagram of FIG.8D is complete.

FIG. 9A illustrates packet processing, according to one embodiment, of aSRv6 packet 320B received by a Segment Routing node having an IP addressthat is the same as the Destination Address 902 of the received SRv6packet 320B. The Segment Routing node operates according to a SegmentRouting function identified from the Destination Address 902 to add theSegment Routing Policy by setting the Destination Address 922 to thefirst Segment Identifier of the Segment Routing Policy, and inserting aSR Header 930 containing the remaining Segment Identifier(s) 932 of theSegment Routing Policy, with its Segments Left set to the number ofthese Segment Identifier(s) 932.

FIG. 9B illustrates packet processing, according to one embodiment, of aSRv6 packet 320B received by a Segment Routing node having an IP addressthat is the same as the Destination Address 902 of the received SRv6packet 320B. Processing is the same as performed in FIG. 9A, despite theSR Header of received SRv6 packet 320B not including a SegmentIdentifier of the value of Destination Address 902.

FIG. 9C illustrates a process according to one embodiment. Processingbegins with process block 990. As determined in process block 991, ifthe Segments Left is greater than zero (in the first/topmost SR Headerof received SRv6 packet 320B), then processing proceeds to process block994; else processing continues to process block 992.

Continuing in process block 994, the Destination Address of the packetis set to the first Segment Identifier of the Segment Routing Policybeing inserted (with the Source Address remaining the same), but thisSegment Identifier is not included in a SR Header being inserted in thepacket. In process block 996, a SR Header is inserted between the outerIP header and the topmost/first SR Header of the received packet, withthe remaining Segment Identifiers of the Segment Routing Policy includedin this SR Header, with its Segments Left to the number of SegmentIdentifiers in this SR Header. Processing proceeds to process block 999.

Continuing in process block 992, the packet is dropped or other errorprocessing is performed. Processing proceeds to process block 999.

Continuing in process block 999, processing of the flow diagram of FIG.9C is complete.

FIG. 10A illustrates packet processing of a packet according to oneembodiment, with reference to network 360 of FIG. 3B.

Node 333 receives and processes SRv6 packet 320C, including sendinggenerated SRv6 packet 320D with Segments Left decreased (by one) withthe resulting value used to identify the corresponding SegmentIdentifier which is used as the Destination Address of SRv6 packet 320D.

Node 334 receives and processes SRv6 packet 320D, including sendinggenerated SRv6 packet 320E. In one embodiment (and shown on the left),Segments Left is decreased (by one) with the resulting value used toidentify the corresponding Segment Identifier which is used as theDestination Address of SRv6 packet 320E. In one embodiment (and shown onthe right), penultimate segment popping of the first/topmost SR Headeris further performed on SRv6 packet 320E before sending to remove the nolonger need SR Header.

Node 335 receives and processes SRv6 packet 320E, including sendinggenerated SRv6 packet 320F, with Segments Left decreased (by one) withthe resulting value used to identify the corresponding SegmentIdentifier which is used as the Destination Address of SRv6 packet 320F.

Node 336 receives and processes SRv6 packet 320F, including sendingdecapsulated IPv6 packet 320G. Segments Left of received SRv6 packet320F is decreased (by one) with the resulting value used to identify thecorresponding Segment Identifier which is used as the DestinationAddress of SRv6 packet 320G. Further, as node 336 is an edge node ofprovider network 330, node 336 will perform penultimate segment poppingof the SR Header thus producing IPv6 packet 320G.

FIG. 10B illustrates a process according to one embodiment to remove ano longer needed SR Header of a packet with multiple SR Headers.Processing begins with process block 1000. In process block 1002, aSegment Routing packet is identified that has multiple SR Headers withthe first/topmost SR Header to be removed. As determined in processblock 1005, if the Segments Left of the first/topmost SR Header is equalto zero, then processing proceeds to process block 1010; otherwise,processing proceeds to process block 1020.

Continuing in process block 1010, the first SR Header is removed. Inprocess block 1012, the Segments Left in the new first/topmost SR Headeris decreased by one. In process block 1014, the Destination Address inthe outer IP header is set to the value of the Segment Identifier at theposition Segments Left in the Segment List of the new first/topmost SRHeader (possibly the only SR header remaining). Processing proceeds toprocess block 1029.

Continuing in process block 1020, the Destination Address in the outerIP header is set to the value of the Segment Identifier at the positionzero of the current first/topmost SR Header. In process block 1022, thefirst SR Header is removed. Processing proceeds to process block 1029

Continuing in process block 1029, processing of the flow diagram of FIG.10B is complete.

In view of the many possible embodiments to which the principles of thedisclosure may be applied, it will be appreciated that the embodimentsand aspects thereof described herein with respect to thedrawings/figures are only illustrative and should not be taken aslimiting the scope of the disclosure. For example, and as would beapparent to one skilled in the art, many of the process block operationscan be re-ordered to be performed before, after, or substantiallyconcurrent with other operations. Also, many different forms of datastructures could be used in various embodiments. The disclosure asdescribed herein contemplates all such embodiments as may come withinthe scope of the following claims and equivalents thereof.

What is claimed is:
 1. A method, comprising: receiving a particularpacket by a particular node in a network, with the particular packetincluding an outer Internet Protocol version 6 (IPv6) header thatincludes a Destination Address; updating said received particular packetaccording to a particular Segment Routing Policy identified based on theparticular packet, with the particular Segment Routing Policy includingan ordered list of Segment Identifiers comprising, in first-to-lastorder, a first Segment Identifier followed by one or more subsequentSegment Identifiers, with said updating including setting theDestination Address to the first Segment Identifier, and with saidupdating including adding said one or more subsequent SegmentIdentifiers, but not the first Segment Identifier, in a first SegmentRouting Header; and sending the particular packet, that includes saidupdates according to the particular Segment Routing Policy while notincluding the first Segment Identifier in the first Segment RoutingHeader, into the network from the particular node.
 2. The method ofclaim 1, wherein the Destination Address of said received particularpacket is a particular Segment Identifier specifying a particular packetprocessing function on the particular node, with said updating saidreceived particular packet performed according to the particular packetprocessing function.
 3. The method of claim 1, comprising: classifyingthe packet resulting in the identification of the particular SegmentRouting Policy, with said updating said received particular packetperformed in response to said identification of the particular SegmentRouting Policy.
 4. The method of claim 1, comprising: classifying thepacket resulting in the identification of a particular packet processingfunction on the particular node, with said updating said receivedparticular packet performed according to the particular packetprocessing function.
 5. The method of claim 1, wherein said receivedpacket is a Segment Routing packet.
 6. The method of claim 1, whereinsaid received particular packet is an IPv6 packet, but not a SegmentRouting packet.
 7. The method of claim 1, wherein said updating saidreceived particular packet includes adding as a last Segment Identifierin the Segment List of the first Segment Routing Header the value, whenthe particular packet was said received by the particular node, of theDestination Address.
 8. The method of claim 1, wherein said updatingsaid received particular packet includes adding a second Segment RoutingHeader with a single Segment Identifier to the particular packet, withthe single Segment Identifier being the Destination Address of theparticular packet when said received by the particular node; and whereinthe particular packet said sent from the particular node includes asequence of three contiguous IPv6 headers in the order of the outer IPv6header, the first Segment Routing Header, and the second Segment RoutingHeader.
 9. The method of claim 8, wherein a bottom packet portion isdefined as from, and including, the Destination Address to the end of anIPv6 packet; wherein said updating the particular packet includesgenerating a top packet portion of the particular packet, with the toppacket portion including the outer IPv6 header, the first SegmentRouting Header, and a preceding portion of the second Segment RoutingHeader including a Segment Left value of one; and wherein the particularpacket said sent from the particular node includes said generated toppacket portion followed by the bottom packet portion of the particularpacket as said received by the particular node.
 10. The method of claim9, wherein said sending the particular packet includes retrieving saidtop and said bottom portions from said contiguous memory locations;wherein said generating the top packet portion includes moving the firsttwenty-four bytes of the received particular packet to the beginning ofsaid contiguous memory locations leaving a matching contiguous insertionspace to the bottom packet portion for the first Segment Routing Headerand the preceding portion of the second Segment Routing Header; andwherein said generating the top packet portion includes storing thefirst Segment Routing Header and the preceding portion of the secondSegment Routing Header in the matching contiguous insertion space. 11.The method of claim 1, wherein said received particular packet is anIPv6 Segment Routing packet including a particular Segment RoutingHeader; and wherein said updating the particular packet includesinserting the first Segment Routing Header in the particular packetbetween the outer IPv6 header and the particular Segment Routing Header.12. The method of claim 11, comprising increasing the Segments Leftvalue by one in the particular Segment Routing Header prior to saidsending the particular packet.
 13. The method of claim 11, wherein saidupdating said received particular packet includes adding as a lastSegment Identifier in the Segment List of the first Segment RoutingHeader, the value, when the particular packet was said received by theparticular node, of the Destination Address.
 14. The method of claim 11,wherein the value, when the particular packet was said received by theparticular node, of the Destination Address is an address of theparticular node.
 15. The method of claim 14, wherein the value, when theparticular packet was said received by the particular node, of theDestination Address is not a Segment Identifier in the particularSegment Routing Header when the particular packet was said received bythe particular node.
 16. The method of claim 1, wherein the firstSegment Routing Header is as an IPv6 Extension header that is the nextIPv6 header after the outer IPv6 header.
 17. A method, comprising:receiving a particular Internet Protocol (IP) packet by a network nodein a network; updating the particular IP packet by the network node toinclude a particular Segment Routing Policy, with the Segment RoutingPolicy including an ordered list of Segment Identifiers that will betraversed by the particular IP packet, with the ordered list comprisingin first-to-last order a first Segment Identifier followed by one ormore subsequent Segment Identifiers, with said updating including addingsaid one or more subsequent Segment Identifiers to a first SegmentRouting Header that is an IP Extension header of the particular IPpacket, and with said updating including setting the Destination Addressof the outer IP header of the particular IP packet to the first SegmentIdentifier; wherein said updating the particular IP packet by thenetwork node to include the particular Segment Routing Policy does notinclude adding the first Segment Identifier to any Segment Routingheader of said received particular IP packet; and sending said updatedparticular IP packet from the network node into the network.
 18. Themethod of claim 17, wherein said updating said particular IP packetincludes adding the value, when the particular IP packet was saidreceived by the particular node, of the Destination Address as a SegmentIdentifier in a Segment Routing Header of the particular IP packet thatis the next in Segment Identifier processing order for said updatedparticular IP packet after said one or more subsequent SegmentIdentifiers.
 19. The method of claim 17, wherein said receivedparticular IP packet is an IPv6 Segment Routing packet including aparticular Segment Routing Header; and wherein said updating theparticular IP packet includes inserting the first Segment Routing Headerin the particular IP packet between the outer IPv6 header and theparticular Segment Routing Header, and increasing the Segments Leftvalue by one in the particular Segment Routing Header.
 20. An apparatus,comprising: one or more hardware interfaces communicatively coupled to anetwork; and one or more network processors with memory associatedtherewith; wherein the apparatus, communicatively coupled to a network,performs packet processing operations including Segment Routing-capable(SR-capable) packet processing operations, with said packet processingoperations including: receiving a particular Internet Protocol (IP)packet from the network; updating the particular IP packet to include aparticular Segment Routing Policy, with the Segment Routing Policyincluding an ordered list of Segment Identifiers that will be traversedby the particular IP packet, with the ordered list comprising infirst-to-last order a first Segment Identifier followed by one or moresubsequent Segment Identifiers, with said updating including adding saidone or more subsequent Segment Identifiers to a particular SegmentRouting Header that is an IP Extension header of the particular IPpacket, and with said updating including setting the Destination Addressof the outer IP header of the particular IP packet to the first SegmentIdentifier; wherein said updating the particular IP packet to includethe particular Segment Routing Policy does not include adding the firstSegment Identifier to any Segment Routing header; and sending saidupdated particular IP packet from the apparatus into the network.